A semiconductor portion of a super junction n-FET (field effect transistor) based on a trench concept typically includes complementary doped layers extending parallel to a flow direction of an on-state current. In the reverse blocking mode, the complementary doped layers generate a wide depletion zone within the semiconductor portion, such that a high reverse breakdown voltage can be achieved even at a comparatively high impurity concentration in the complementary doped layers. It is desirable to improve the avalanche ruggedness of super junction semiconductor devices.